A cutting blade of a rotary cutting tool such as a drill and an end mill is worn out when used. Therefore, after the cutting performance decreases or a prescribed period of use elapses, a cutting head including at least the cutting blade is replaced with a new cutting head. At this time, if the cutting head is attached to a superhard shank in a non-removable manner, the superhard shank must be replaced together at the timing of replacement of the cutting blade, even when replacement of the superhard shank is unnecessary because the superhard shank does not reach the end of the service life. Such replacement of the superhard shank is not preferable in terms of cost because the superhard shank is relatively expensive.
Thus, it is conceivable to removably attach the cutting head to the superhard shank so as to be able to replace only the cutting head when the cutting blade is worn out. PTD 1 describes that a construction having a superhard structure, which is to be processed into a cutting blade, is attached to a tool carrier. Specifically, attaching means such as a thread groove for brazing the above-described construction and the tool carrier is, for example, provided in the above-described construction, which makes it possible to attach the above-described construction to the tool carrier.